Selected Abstracts

EXPERIMENTAL PHYSIOLOGY, Issue 7 2008Andrew C. Betik
The Fischer 344 × Brown Norway F1-hybrid (F344BN) rat has become an increasingly popular and useful strain for studying age-related declines in skeletal muscle function because this strain lives long enough to experience significant declines in muscle mass.
Since exercise is often considered a mechanism to combat age-related declines in muscle function, determining the utility of this strain of rat for studying the effects of exercise on the ageing process is necessary.
The purpose of this study was to evaluate the plasticity of skeletal muscle aerobic function in late middle-aged male rats following 7 weeks of treadmill exercise training.
Training consisted of 60 min per day, 5 days per week with velocity gradually increasing over the training period according to the capabilities of individual rats.
The final 3 weeks involved 2 min high-intensity intervals to increase the training stimulus.
We used in situ skeletal muscle aerobic metabolic responses and in vitro assessment of muscle mitochondrial oxidative capacity to describe the adaptations of aerobic function from the training.
Training increased running endurance from 11.3 ± 0.6 to 15.5 ± 0.8 min, an improvement of ,60%.
Similarly, distal hindlimb muscles from trained rats exhibited a higher maximal oxygen consumption in situ (23.2 ± 1.3 versus 19.7 ± 0.8 ,mol min,1 for trained versus sedentary rats, respectively) and greater citrate synthase and complex IV enzyme activities in gastrocnemius (29 and 19%, respectively) and plantaris muscles (24 and 28%, respectively) compared with age-matched sedentary control animals.
Our results demonstrate that skeletal muscles from late middle-aged rats adapt to treadmill exercise by improving skeletal muscle aerobic function and mitochondrial enzyme activities.
This rat strain seems suitable for further investigations using exercise as an intervention to combat ageing-related declines of skeletal muscle aerobic function.
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INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 3 2007Sandra Bonache
Abstract
Evaluation of the possible implication of the SDHA, SDHB, SDHC, SDHD and CS genes in non-obstructive male infertility was performed on the basis that sperm concentration in the ejaculate has been previously correlated with nuclear-encoded mitochondrial enzyme activities (the four subunits of succinate dehydrogenase/complex II of the respiratory chain and citrate synthase).
We performed an exhaustive analysis of the five genes for the presence of sequence variants that could be associated with impairment of sperm production. blastn searches in the genomic sequence NCBI database evidenced the presence of highly homologous sequences elsewhere on the genome that can interfere with polymerase chain reaction experiments.
Therefore, a careful design of the analytical strategy to search for sequence variants was performed.
In this report, we provide primer sequences that allowed selective amplification of coding and immediate flanking regions of the five genes.
Fifty-five sequence variations in the five genes were identified in infertile and normozoospermic fertile individuals as controls and only one of them (SDHA c.456+32G>A) showed significant genotype association with impairment of sperm production.
Moreover, new single nucleotide polymorphisms identified should be useful in future association studies for other human diseases related to nuclear-encoded genes, leading to mitochondrial respiratory chain activity impairment revealing the physiological role of these genes.
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JOURNAL OF ANATOMY, Issue 2 2000PER S. STĹL
Four human soft palate muscles, and palatopharyngeus, the uvula, the levator and tensor veli palatini were examined using enzyme-histochemical, immunohistochemical and biochemical methods and compared with human limb and facial muscles.
Our results showed that each palate muscle had a distinct morphological identity and that they generally shared more similarities with facial than limb muscles.
The palatopharyngeus and uvula muscles contained 2 of the highest proportions of type II fibres ever reported for human muscles.
In contrast, the levator and tensor veli palatini muscles contained predominantly type I fibres.
A fetal myosin heavy chain isoform (MyHC), not usually found in normal adult limb muscles, was present in a small number of fibres in all palate muscles.
The mean muscle fibre diameter was smaller than in limb muscles and the individual and intramuscular variability in diameter and shape was considerable.
All palate muscles had a high capillary density and an unusually high mitochondrial enzyme activity in the type II fibres, in comparison with limb muscles.
No ordinary muscle spindles were observed.
The fibre type and MyHC composition indicate that the palatopharyngeus and uvula muscles are functionally involved in quick movements whereas the levator and tensor veli palatini muscles perform slower and more continuous contractions.
The high aerobic capacity and the rich capillarisation suggest that the palate muscles are relatively fatigue resistant.
Absence of ordinary muscle spindles indicates a special proprioceptive control system.
The special morphology of the palate muscles may be partly related to the unique anatomy with only one skeletal insertion, a feature consistent with muscle work at low load and tension and which may influence the cytoarchitecture of these muscles.
Other important factors determining the special morphological characteristics might be specific functional requirements, distinct embryological origin and phylogenetic factors.
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ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2009K. FREDRIKSSON
Background: Mitochondrial derangements in muscle of patients suffering from sepsis have been established in several studies and have been related to muscle dysfunction and organ failure.
It is not possible to study the early phase of sepsis in patients; therefore, we used a human endotoxaemia model to study the effect of early sepsis on muscle mitochondria.
Methods: Seven healthy male volunteers received a standardised endotoxin challenge.
Muscle biopsies were obtained immediately before the challenge, and at 2 and 4 h following the endotoxin challenge.
The muscle biopsies were analysed for maximal activities of citrate synthase and complexes I and IV of the respiratory chain.
In addition, total and mitochondrial superoxide dismutase (SOD) activities were analysed.
The concentrations of ATP, creatine phosphate and lactate were analysed to assess the cellular energy status.
Total and phosphorylated AMP-activated protein kinase (AMPK-P), a key regulator in intracellular energy metabolism, was measured.
Results: Activities of citrate synthase and complex I were significantly increased 2 h after the endotoxin challenge.
SOD activities were unaffected by the endotoxin challenge.
No changes in ATP, creatine phosphate or lactate were observed.
Neither total nor AMPK-P changed.
Conclusions: An endotoxin challenge given to healthy volunteers rapidly increases mitochondrial enzyme activity in skeletal muscle.
The results of this human model indicate that possibly early during sepsis, mitochondrial activity might be increased in contrast to what has been shown in the later phases of sepsis.
It is possible that this early activation leads to exhaustion of the mitochondria and a decreased function later during sepsis.
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A comparison of the in vitro cytotoxicity of two root canal sealers

JOURNAL OF ORAL REHABILITATION, Issue 4 2003M. Dartar Öztan
summary, The purpose of this study was to compare the cytotoxicity of an epoxy resin-based sealer (AH Plus) and a silicone-based sealer (Roeko Seal Automix, RSA).
Cytotoxicity was assessed using the MTT assay for mitochondrial enzyme activity and haemocytometer viable cell counting after 24, 48 and 72-h exposure to L929 cells.
AH Plus and RSA showed no statistically significant difference in the degree of toxicity.
Both sealers had a low toxic influence on the cells during the experimental period.
This study indicates that epoxy resin-based sealer AH Plus and the silicone-based sealer RSA have similar levels of cytotoxicity to mouse fibroblasts.
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